Learn on PengiEureka Math, Grade 4Chapter 24: Fraction Addition and Subtraction

Lesson 2: Use visual models to add and subtract two fractions with the same units, including subtracting from one whole.

In this Grade 4 Eureka Math lesson from Chapter 24, students use visual models such as tape diagrams and number bonds to add and subtract two fractions with the same units, including subtracting a fraction from one whole. Students practice recognizing equivalent fractions, decomposing mixed numbers, and writing related addition and subtraction sentences using like-denominator fractions. The lesson builds toward fluency with fraction operations through hands-on drawing activities and guided concept development.

Section 1

Model Subtracting a Fraction from One on a Number Line

Property

To subtract a fraction from one whole, first rename 1 as a fraction with the same denominator as the fraction being subtracted.
Then, subtract the numerators.

1−ab=bb−ab=b−ab1 - \frac{a}{b} = \frac{b}{b} - \frac{a}{b} = \frac{b-a}{b}

Examples

Section 2

Subtracting a Fraction from a Mixed Number

Property

To subtract a fraction from a mixed number like 1ac−bc1 \frac{a}{c} - \frac{b}{c} (where bc>ac\frac{b}{c} > \frac{a}{c}), you can use two methods:

  1. Subtract from the Total: Convert the mixed number to an improper fraction and then subtract.
1ac−bc=c+ac−bc=c+a−bc1 \frac{a}{c} - \frac{b}{c} = \frac{c+a}{c} - \frac{b}{c} = \frac{c+a-b}{c}
  1. Take from 1: Decompose the mixed number, subtract the fraction from the whole number part, and add the fractional part back.
1ac−bc=(1−bc)+ac=(cc−bc)+ac1 \frac{a}{c} - \frac{b}{c} = (1 - \frac{b}{c}) + \frac{a}{c} = (\frac{c}{c} - \frac{b}{c}) + \frac{a}{c}

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Chapter 24: Fraction Addition and Subtraction

  1. Lesson 1

    Lesson 1: Use visual models to add and subtract two fractions with the same units.

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  2. Lesson 2Current

    Lesson 2: Use visual models to add and subtract two fractions with the same units, including subtracting from one whole.

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  3. Lesson 3

    Lesson 3: Add and subtract more than two fractions.

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  4. Lesson 4

    Lesson 4: Solve word problems involving addition and subtraction of fractions.

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  5. Lesson 5

    Lesson 5: Use visual models to add two fractions with related units using the denominators 2, 3, 4, 5, 6, 8, 10, and 12.

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  6. Lesson 6

    Lesson 6: Use visual models to add two fractions with related units using the denominators 2, 3, 4, 5, 6, 8, 10, and 12.

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Lesson overview

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Section 1

Model Subtracting a Fraction from One on a Number Line

Property

To subtract a fraction from one whole, first rename 1 as a fraction with the same denominator as the fraction being subtracted.
Then, subtract the numerators.

1−ab=bb−ab=b−ab1 - \frac{a}{b} = \frac{b}{b} - \frac{a}{b} = \frac{b-a}{b}

Examples

Section 2

Subtracting a Fraction from a Mixed Number

Property

To subtract a fraction from a mixed number like 1ac−bc1 \frac{a}{c} - \frac{b}{c} (where bc>ac\frac{b}{c} > \frac{a}{c}), you can use two methods:

  1. Subtract from the Total: Convert the mixed number to an improper fraction and then subtract.
1ac−bc=c+ac−bc=c+a−bc1 \frac{a}{c} - \frac{b}{c} = \frac{c+a}{c} - \frac{b}{c} = \frac{c+a-b}{c}
  1. Take from 1: Decompose the mixed number, subtract the fraction from the whole number part, and add the fractional part back.
1ac−bc=(1−bc)+ac=(cc−bc)+ac1 \frac{a}{c} - \frac{b}{c} = (1 - \frac{b}{c}) + \frac{a}{c} = (\frac{c}{c} - \frac{b}{c}) + \frac{a}{c}

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 24: Fraction Addition and Subtraction

  1. Lesson 1

    Lesson 1: Use visual models to add and subtract two fractions with the same units.

    LearnPractice
  2. Lesson 2Current

    Lesson 2: Use visual models to add and subtract two fractions with the same units, including subtracting from one whole.

    LearnPractice
  3. Lesson 3

    Lesson 3: Add and subtract more than two fractions.

    LearnPractice
  4. Lesson 4

    Lesson 4: Solve word problems involving addition and subtraction of fractions.

    LearnPractice
  5. Lesson 5

    Lesson 5: Use visual models to add two fractions with related units using the denominators 2, 3, 4, 5, 6, 8, 10, and 12.

    LearnPractice
  6. Lesson 6

    Lesson 6: Use visual models to add two fractions with related units using the denominators 2, 3, 4, 5, 6, 8, 10, and 12.

    LearnPractice